How to take measurements for the CHARM rain gauge network

  1. Mount gauge at eye level in an open area away from trees and buildings which might block rain from entering the gauge.
  2. Take daily measurements, preferably at 1200 UTC (6:00am local standard time or 7:00am local daylight savings time). If you cannot read gauge at this time, read it at the time you can, noting beginning and ending time of observation.
  3. Rain measurements are for the previous 24 hours. For example, rain that occurred on the afternoon of the 11th of February for instance would be reported for the period of the 11th at 6 am through the 12th at 6 am. (Note during daylight savings time, observations would be at 7 am.)
  4. Enter rainfall data into CHARM database at http://weather.msfc.nasa.gov/charm/charm.html
  5. Keep a hardcopy of your rain records either on a calendar or a sheet of paper. You might even keep this in your own spreadsheet.
  6. Do not leave rainwater freeze in the inner cylinder of the 4" plastic rain gauges. They will shatter. In cold (potentially freezing) weather, the inner tube and funnel may be removed and rain/snow can be collected in the outer tube. Use inner tube to measure collected rain.
  7. Collected snow should be allowed to melt, measured, and reported as "water equivalent." To aid melting, you may place the outer cylinder in a bath of cool or warm water. Do not place a cold gage in hot water.
  8. Use comment section on CHARM data entry to note abnormal events (e.g., "it rained but I spilled some while I was measuring", or "1 in of snow, 0.09 water equivalent", etc.)
  9. Only report precipitation in the form of rainfall or snowfall. Although you’re welcome to note dew or fog deposition in your notes, please do not report it as precipitation.

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Technical Contact and Page Curator: Kevin M. McGrath (kevin.m.mcgrath@nasa.gov)
Responsible Official: Dr. Gary J. Jedlovec (gary.jedlovec@nasa.gov)

Last Updated: January 9, 2011